So, I'm not sure how many people are on this website. I just made this account today.
I was going to start working on a historical map of the Chicago "L" Train system based on year.
Are we allowed to contribute to the building of the time/date slider?

A history of the Elevated system would be fantastic - are you a coder & still interested? This is one of the more important needs for development. We have github accounts here: https://github.com/OpenHistoricalMap